Skip to main content

Full text of "The Cambridge Natural History"

See other formats

xii                          THE BELUGA AND NARWHAL                       373
The Beluga is a northern species purely. The reputed form,
2?. Mnff-ii, was said to come from Australian         ; but there
seems to have been an error in this statement. It is interesting
to note that the white colour, so characteristic of the genus
and species, is not found in the young, which are blackish. They
gradually pale as they advance towards maturity. Delphin-
apterns leucas reaches a length of 10 feet, and like other
Porpoises will ascend rivers in search of food. It is said to
be specially addicted to salmon. Among the contents of the
stomach have been found quantities of sand. But this habit of
swallowing sand or pebbles has been noted in other Whales.
Whether it is or is not accidental (taken in with ground-living
food), it seems hardly likely that it is used for purposes of
ballast! The Beluga has a voice ; but the name " Sea Canary "
is hardly suitable to it. A specimen of this species., recently
described from the shores of Scotland (it is often thrown up
upon our coasts)* which had got entangled in the stakes of a new
net, was regarded by the natives, on account of its white colour,
as a ghost. Externally, besides its colour, the Beluga is remark-
able for possessing a distinct neck, which is correlated of course
with the freedom, of the cervical vertebrae, and is also seen in
The Narwhal (Mbnodon) is closely allied in structure to the
last geniia It has the following anatomical characters:—The
teeth are reduced to a single *c horn," in the upper jaw, which
is rudimentary in the female. The neck vertebrae are free. The
vertebral formula is O 7, D 11, L 6, Ca 26. The pterygoids
are as in Delphinaptem&> and, as in that genus, there are no hairs
upon the face or dorsal fin.
This genus is of course most obviously characterised by the
twisted tosk of the male, which is occasionally double. This
tusk has given to the only species of the genus, J£ mon&cerost
both its generic and specific name. The animal has a spotted
colour; but, as in the case of the Beluga, old animals tend to
become white. The use of its horn to JSfonodon has been
debated. In the first place it is clearly a secondary sexual
character. The males have been observed to cross their horns
like rapiers in a fencing match. It may be that they are used in
more serious combats* An ingenious suggestion is that the long
and strong tusk enables its possessor to break the thick ioe and